Doctors at a press conference in Oslo today revealed that Alexander dale One, the world 100m breaststroke champion who died on the last day of April, suffered a heart attack caused by a blood clot in one of his coronary arteries.

The results of a full autopsy into the Norwegian swimmer's death during a high-altitude training camp in Flagstaff, Arizona, led Dr. Eivind Berge, a cardiologist specialising in the field, to say that coronary artery disease of this kind is highly unusual in young athletes and the young in general.

High cholesterol, smoking, obesity or inactivity are associated with the condition, as are factors that may cause thickening of the blood. The doctor noted that Dale Oen had slightly increased cholesterol levels, but no other known risk factors.

The doctor was apologetic, saying that the problem might have been related to a shoulder injury Dale Oen was treated for in January. Earlier understanding of that and intervention might have prevented his death.

The autopsy revealed that, up to two months before his death, Dale Oen experienced changes to heart muscle consistent with small infarctions.

The full autopsy report is, in a sporting context, likely to draw more questions on how Alex Dale Oen died, if only in the interests of prevention.